1. Field of the Invention
The present invention relates generally to natural gas well production apparatus. More particularly, the present invention relates to apparatus for the storage and delivery of methanol to natural gas wells.
2. Related Art
It is current practice to inject methanol into gas wells to reduce, and in most cases prevent, the formation of ice plugs in the well. This requires the placement of chemical tanks in which to store the methanol near the head of each gas well to be treated. These tanks are commonly five hundred gallon chemical storage tanks. The tanks are usually periodically filled with methanol from a tank truck that can travel from tank to tank, and each tank is filled through a hose extending from the truck to the tank. The methanol is then pumped from the tank and into the well by high pressure pumps creating pressures greater than 1000 psi to force the methanol into the wells. The methanol mixes with the gas flowing up the well in sufficient amounts to prevent hydrate formation in the well and wellhead. Hydrate formation in the well and wellhead is generally the cause of the ice plugs. The injection of methanol into the wells generally prevents formation of these ice plugs.
Currently, the chemical tanks for storing the methanol are mounted out of doors near the wellheads. Regulations generally require that the chemical tanks be mounted in a containment container so that any leakage from the tanks can be collected and contained and does not merely flow from the tanks onto and into the ground. The containment containers for possible leakage, when located outdoors, have to have a capacity at least fifty percent more than the capacity of the tank. Thus, with a five hundred gallon tank, the containment container must have a capacity of at least seven hundred and fifty gallons.
Current practice is to place the chemical tank in a cattle watering trough to catch any chemical that spills or leaks from the tank. FIG. 1 shows such a methanol tank installation with chemical tank 1 in a cattle watering trough 2. However, many gas well locations, such as for gas wells in Eastern Utah and in Wyoming, are in remote range land areas where wildlife roam and where cattle roam. Cattle and other animals that roam these areas are accustomed to drinking from such cattle water troughs. By being out of doors, the troughs under the outdoor tanks can collect and fill with water when it rains. Cattle and other animals will drink water from the troughs, and, if chemical has spilled into a trough, it can kill or sicken the cattle or other animals which drink from the contaminated trough. Therefore, currently troughs with chemical tanks mounted therein are usually covered with netting 3 to keep small animals, snakes, and birds from the tough, and are surrounded with railings or other fencing 4 to keep cattle or other live stock and large wild mammals from the trough (again, see FIG. 1). The pumps 5 used to pump the methanol into the wells may be located adjacent the tanks, inside or outside the trough, but within the railings or fencing 4 surrounding the trough. FIG. 1 shows such a pump mounted on and supported just above the ground outside of the trough. Being out of doors exposes the tanks and pumps to the elements, which can damage the tanks and particularly the pumps. Also, the location of the pumps within the railing or fence and close to the ground can make service and repair of the pumps difficult.
When tanks and pumps are mounted out of doors in these remote areas, they are often used as targets by hunters or others who may also roam these areas, which may result in damage to the tanks and pumps. In addition, the outdoor pumps, which generally cost upwards of two thousand dollars each, become targets for theft.
In addition, in this era of environmental protection, the appearance of chemical storage tanks in a cattle trough with railing or fencing there around, and with associated piping and pumps, can be offensive and objectionable to some. The typical range storage tank and outdoor containment container takes up approximately fifty square feet of space, and, because the containment container it is generally round, the perceived footprint is even larger.
There remains a need for a better system of methanol storage at individual gas well heads.